public static List <Triangle3D> SplitPlaneTriangleIntersection(Plane3D plane, Triangle3D inTriangle, double epsilon = 1e-7)
{
Polygon3D poly = new Polygon3D();
poly.vertices.Add(inTriangle[0]);
poly.vertices.Add(inTriangle[1]);
poly.vertices.Add(inTriangle[2]);
Polygon3D front;
Polygon3D back;
var res = poly.SplitWithPlane(plane, out front, out back, true);
var triangleList = new List <Triangle3D>();
if (res != Polygon3D.SplitType.SP_Split)
{
triangleList.AddRange(new[] { inTriangle });
return(triangleList);
}
var polygons = new[] { front, back };
foreach (var p in polygons)
{
int offset = 0;
if (p.vertices.Count > 3)
{
double o0a0 = new Triangle3D(p.vertices[0], p.vertices[1], p.vertices[2]).ComputeArea();
double o0a1 = new Triangle3D(p.vertices[0], p.vertices[2], p.vertices[3]).ComputeArea();
double o1a0 = new Triangle3D(p.vertices[1], p.vertices[2], p.vertices[3]).ComputeArea();
double o1a1 = new Triangle3D(p.vertices[1], p.vertices[3], p.vertices[0]).ComputeArea();
// find optimat split by taking the least difference between triangle areas
if (Math.Abs(o0a0 - o0a1) > Math.Abs(o1a0 - o1a1))
{
offset = 1;
}
}
for (int i = 2; i < p.vertices.Count; i++)
{
triangleList.Add(new Triangle3D(p.vertices[offset],
p.vertices[(i - 1 + offset) % p.vertices.Count],
p.vertices[(i + offset) % p.vertices.Count]
));
}
}
return(triangleList);
}
